A paper-made reel used for winding a flexible linear body such as a tube, a hose, or an electric wire is publicly known as disclosed in, for example, PTLs 1 to 4.
This reel is formed of paper such as corrugated cardboard or thick paper, has a cylindrical winding drum for winding the flexible linear body, and flange plates attached to both ends in the axial direction of the winding drum, and has the advantage that disposal after use is easy. However, since the strength of the winding drum and a core is weak, various contrivances have been made to enhance the strength.
For example, in the reel disclosed in PTL 1, the strength of the reel is increased by forming the winding drum in an inner and outer double structure. In the reel disclosed in PTL 2, a plurality of annular reinforcing plates are fitted into the inner central position of the winding drum, and the winding drum is supported from the inside by the reinforcing plates.
In the reel disclosed in PTL 3, a support member having a square hollow shape is formed by folding corrugated cardboard, this support member is inserted into a cylindrical winding drum and is caused to support from the inside, and the strength of the winding drum is thereby enhanced.
The winding drum of the reel disclosed in PTL 4 is formed by fitting a plurality of annular reinforcing partition plates on the outer periphery of a cylindrical shaft portion core at a regular interval, and wrapping a cylindrical reinforcing shaft core around the outer peripheries of the reinforcing partition plates.
However, in the reels disclosed in PTLs 1 to 3, the strength of the cylindrical winding drum has not been improved to such an extent that it can sufficiently withstand the large tightening force acting through the linear body at the time of winding or unreeling of the linear body. In addition, they have a problem in that it is structurally difficult to uniformly increase the strength of the winding drum over the entire axial direction. Room for further improvement is left.
On the other hand, in the case of the reel disclosed in PTL 4, the strength of the winding drum is considered to be high compared to the reels disclosed in PTLs 1 to 3. However, since the winding drum is formed by combining many separately formed components including the shaft portion core, there is a disadvantage that the structure is complicated and the assembly work is complicated.